This took considerable time to solve and thought to post a potential solution that may occur with others in a same scenario.
Gear: MS Surface Pro 4 Win10/with i7/8gig ram / SSD connected to a 12TB Western Digital Drive via CAT 6
Sound card connection - 2 ways: via Mini DV port to HDMI (port #5 on Denon AVR4200 Receiver - 24/192 DAC) and also via USB to an SB-X 5.1 Surround Creative Labs (24/96 DAC) which connects via Optical Cable to same Port #5. (you can assign two connections on this receiver to same port)
This allows the toggling of either sound output device with Direct Sound digitally by using the Output drop down menu or the DS: Primary option is another choice.
Installed components with Foobar 1.41: Channel Mixer, Resampler SoX set to Best and highest 192k, EQ (usually fla but alter on as needed basis) and Advanced Limiter. No DSD (disabled) usage straight PCM to allow for the SB-X or the Denon to handle the decoding. I prefer the Channel Mixer (to create profiles and tweak) vs. the components such as Convert Stereo to Quad or some of the others but I do swap frequently for comparisons.
I've been playing off the Microsoft Surface battery (mostly) as I unplug the tablet and move into the Theater Room where our 5.1 sound is setup.
All has been happy and well until yesterday. I had opened VLC after finding that Foobar was unable to manage (that I am aware) BDMV files and also ISO's encoded for Blu-Ray.
I had finished with VLC after about 15 minutes and then re-opened Foobar and played a 5.1 ISO audio file which had always played fine. The degradation of sound was noticeable. Dull with hiss especially in the center channel. However 2ch SACD (24/96 or 24/192) played fine with exact same settings as did MP3's etc. Upmix to 5.1, Stereo, any combo no issues.
After numerous and endless testing with plugging and unplugging of cables, drivers for all hardware sources, disabling all components, reinstalling Foobar and so on, the solution was simply to plug in the A/C cord to the Surface Tablet. The white noise / hiss on ISO 5.1 files was resolved. (no out of memory error messages BTW - I tend to keep almost everything closed though I didn't monitor every background process). All I can attribute is perhaps the file size of the ISO across the network and heavier demand on the CPU caused the drain in battery mode only (?). I'll add the prior evening, running Sirius XM through the tablet into our other sound system caused it to go off after 15 minutes as that's the default Power Plan - to sleep after 15 mins on battery. I moved this to 1 hour and Sirius played fine. The following morning (today) I moved the tablet back to the 5.1 surround sound system, it played VLC fine with DVD-Audio and Blue-Ray - nice clean 5.1 sound. About 20 minutes after I re-opened Foobar and this was when I first noted the white noise Hiss issue and thus I can confirm is specific to Foobar since VLC had no issues with 5.1.
The issue appears resolved though I'll continue to monitor. Anyone else with hiss on ISO 5.1 files only out there?
I recently installed vb audio cable asio bridge for my use with Spotify, and as well the sound can goes direct into my dac which is also a bit particular.
Yes in asio bridge I chose the component for foo ar I installed and used until now . said DSDTranscoder .
my dac is an audiophonics sabre ess9028q2m ,
but with foobar2000 now and vb audio cable sio bridg installed, I must choose another output in foobar2000 preferences. because ASIO in foobar didn't worked anymore.
The in foobar the only option's working is KS which means the kernel streaming , .
did i done right ?
my dac is usb dsd XMOS U208.
tye fact is I'm absilutely nit interested in dsd nor hd files.
but the dac needs to go in an output like asio or sometimes even pass though dsd , because without using dsd processor which is inside the dac, you can't have access filterings that are essentials or seems essentials etc, to avoid bad sound or what else .
My question is also should I try to use the wasapi out ? that said usually without vb audio installed my dac doesn't work i asio, or not very well because on ly asio mode seems let the sound going to the dsd processor' dac.
P.S : it often happens that simple setup of this kind of dac is not clearly explains on forums , or often goes with stuffs like dsp correction oversampling etc...
not my aim, my files audio I read is most 16-44khz. though upsampling or whatever eg 16 44 khz to dsd 32bits 384khz etc ... is absolutely not my aim .
I usually record vinyls in DSD 5.6 Mhz 1bit format and then I convert it with TEAC/TASCAM Hi-Res Editor to WAV 192/32bit float to have the sound as analogue as possible and to make further optimizations with Adobe Audition 3.0 (denoise, remove clicks and crackles, Bass, Mid, Treble calibration, compression, normalization,...). Then, I use this 192/32bit wav "master tape" for archiving (wavpack) and for convert it to 48/32float WAV for auditions or for smartphone HQ mp3s.
If & When the Zombie Apocalypse Happens
You will probably regret wasting your Time on such a pointless Exercise.
This is the only option I see in the preferences:File -> Preferences -> Advanced -> Decoding -> HDCD Decoder -> Halve output volume.
Enable decode postprocessing - for decoding DTS, HDCD, etc.
Refer to the documentation of installed optional components for details.